Sulfur-containing compounds are common contaminants of crude oil and natural gas. While most sulfur-containing compounds are removed prior to refining the crude oil and natural gas, some sulfur-containing compounds end up in the refined products. Specific to gasoline, sulfur-containing compounds are eventually converted into sulfur oxide during the process of fuel combustion in vehicles and other devices. The sulfur oxide is toxic for humans as well as for catalytic converters used in most vehicles in the United States. The US EPA regulates sulfur in fuels, and the upper limit has been tightened over the years (from ˜300 ppm before 2000 to the current EPA mandated level of ˜30 ppm of sulfur). In 2017, the EPA plans to curb acceptable sulfur levels further down to 10 ppm from the current 30 ppm level. This can require developing better refining solutions for removal of sulfur-containing compounds from fuel. Moreover, it would also be desirable to develop a cost-efficient technology to detect sulfur-containing compounds at a part-per-million (ppm) level in an organic medium with chemical specificity. The systems and methods discussed herein address these and other needs.